Wow, first bilge-keel Hunter I have seen at low tide!!. Nice bottom paint!! By the way my wife and I got back 2 years ago from living in Tenby, Wales overlooking Caldey Island for 3 years. Back to your question, no but I would start with dinghy davit manufacturers as they have extensive list of Hunter sailboats their davits have been installed on and can offer technical advice on mounting the davits to avoid your life raft fitted to port stern side.
I assume you can access to the port aft locker to install the backing plate. As you can see in the photo below, the Ocean Marine's dinghy davit is attached to the outside edge of the transom and rail. You can also attach it to the arch to provide additional lateral support as I did.
Manufacturers include: Garhauer, Kato, Forespar Nova, Edson Marine, Mar-Tek, Ocean Marine, St. Croix, Sailboatowner, Batsystem and Atlantic Towers to name a few. Look for a 316 stainless steel(or sch 80 aluminum from Atlantic Towers) and a manufacturer that has supplied one to a Hunter 31 bilge-keel.
